Piston packing



W. E. OSHEI Oct. 7, 1952 PISTON PACKING Filed Oct. 25, 1949 A ttorneyJ.

Patented Oct. 7, 19512 Application October 25, 1949, Serial No. 123,368

Y In Great Britain June 30, 1948 21 claims. 1

The present invention relates to uid pressure motors of the oscillating paddle type as described for example -n British specifications Nos. 237,455

Vand 546,483. Such motors are generally designed for operation by suction and are used extensively for driving the windscreen wiper on a vehicle. More particularly, the invention relates to the construction of the paddle and to a method of assembling the paddle in the paddle chamber of the motor.

Such paddles have hitherto been constructed of two cupped packing members made of leather and of generally rectangular shape, the two cupped leather members being assembled with their anges facing one another and spaced by a pair of anged inner metal plates which embrace the transverse shaft about which the paddle rocks, two further metal plates being tted outside the cupped leathers and the whole assembly being secured together by transverse rivets. This construction is illustrated in British specifications Nos. 237,455 and 444,452.

The paddle leathers are greased' when the motor is assembled but after a time leathers become hardened. This hardening of the leathers appears to `be due to moisture getting into the paddle chamber and forming an emulsion with the lubricant. Moisture gets into the paddle chamber by reason of the fact that the motor, when used for driving a windscreen wiper, isin use during rainy and damp Iweather as result of which damp `air is sucked into the motor, and in some casesrain on the driving shaft may also be sucked intothe motor through the shaft bearing. Since windscreen wiper motors remain out of use "for long periods of time, particularly during spells of dry Weather, the cupped leathers harden with a permanent set corresponding with the dimensions of that part of the paddle chamber in which the paddle rests in its parked position. As a result the paddle will not flex toconform with the surface of the -paddle chamber when the paddle moves into another part of the chamber, for example when the motor'is operating, as a result of Which air leakage takes place around the leathers with consequent loss of power of the motor. To overcome this diculty,`spring expanders are generally tted inside the flanges of the cupped leathers as described for example in British specication No.v 306,381, With the object of expanding the flanges into close contact with the wall of the piston chamber, but this has not proved a complete solution of the problem. Moreover, the provision of expanders increases the friction between the cupped leathers and the wall 2 of the paddle chamber which reduces the power of the motor and necessitates a higher minimum vacuum before the motor operates. This is adisadvantage with suction operated windscreen wiper motors since the available suction on a vehicle is sembly with the otherr components of the paddle and before assembly of the paddle'lunt within the paddle chamber. This necessitates careful forming of the `paddle leathers to avoid the forma.

tion of wrinkles around the flanges, particularly at the curved corner portion thereof, and to ensure that they will closely conform to the internal shape ofthe paddle chamber of the motor. In assembling the paddle unit in the paddle chamber, the paddle is swung` from one to the other of its limiting positionsl to make sure that the leathers are properly assembled. A, dummy top cover, Which is open to permit inspection, is fitted beforethe proper cover is fitted, and any part of the paddle which becomes nipped between the dummy cover and the top edge of the paddle chamber is `carefully trimmed off before the proper cover is fitted. The fitting,4 of the paddle unit thus necessitates employing .askilled an vide an improved paddle, and an improved method of assembling the paddle within the ypaddle chamber which permits employing less skilled operators than has hitherto been necessary. To this end, from one aspect, the invention consists in a fluid pressure motor of the oscillating paddle type, in which the cupped packing members are made of rubber-like material, and wherein members of plates of metal or other substantially rigid material, are secured over the outer surfaces of the packing members, said members or plates being of such a size that the clearance between the periphery of an outer member or plate and the wall of the paddle chamber is insufcient to permit the ilangeto be sucked or otherwise moved vso that it, or apart thereof, can face in the opposite direction t0 that in Whichit is designed to operate. Since it is desirable to lubricate the paddle with grease, the materialfrom which the packing members are made preferably possesses oil-resistant properties so that it does notfbecome perished by the lubricant. Preferred materials for the packing members are polyvinyl chloride, neoprene, or the material known under the registered trade-mark Buna. Such materials are furthermore lubricated by water, so that the moisture entering the paddle chamber assists in lubricating the paddle packings without hardening them.

By making the packing members of such materials, the elastic properties thereof enable the same to distort and flex to conform with the inner surface of the paddle chamber without the formation of wrinkles. Furthermore, the increased ilexibility'of the flanges of the packing members enables the suction to hold the flanges in close and substantially leakproof contact with the wall of the paddle chamber Without the necessity of spring expanders. Thus the invention not only reduces leakage past the paddle but also reduces the friction between itrandthepaddie chamber, and thus providesa motor which is able to operate on lower degrees of-vacuumv than has hitherto been possible.

Due to the highly ilexible nature of the-material from which the packing members are made, there sfa tendencypfor'the suction to pull upon thecupped flanges, andpullthe packings "insideout',thatis to say to'pulljtheilanges from dtheir desired inwardly facing direction so that` they face in thereversedirection., The, rubbing of' the edge of the flange on the wall of the paddle chamber also produces asimilar tendency. To avoid this undesirablereversal of thepackings, outer'memberssor plates of metal or'other substantially rigid material aresecured .over the outer surfaceszof the. packing members, said platesbeing of such a sizevthat the clearance between the periphery of an outer plateand the wall ofthe paddle chamber is insufficient to permit `the flange -to be sucked orotherwise. moved so that it, or a part thereofcan face in theopposite direction `to that in which it isdesigned to operate. .The clearance between the` peripheryA of an outer plate and the wall of the chamber maybe suchthat it does not substantially exceed, and is preferably less than, the thickness of` thematerial ofthe flange of the adjacent packingmember at 'all points around saidperiphery, although it willbe obvious that smally portions ofthe periphery may be cut awayor notched providedI that the gap thus formedis-not large enough to permit'the-adjacent part of the flange to be turned inside out-under the operating conditions of the motor. The plate members may, of course, be apertured or perforated-at their inner regions.

TheA packing members may bepreformed, for example by moulding, to a cupped shape. Preferably, however, the packing members are initiallymade ilat, for example by being cut from sheet material, with a size which is greater than the cross-section of the paddle chamber of the motor, the peripheralzones of the packing members being foldedover to-forrn the cupped flanges byinserting thepackings into the paddle chamber after they have been assembled into the paddle unit. In this way the packings conform to the actualY contour ofthe paddle chamber, and

due to the elastic nature of the material from which the packings are made, the material compresses around the curved corners ofthe flanges and the production of. wrinkles does not take place. Furthermore, with this construction, the elastic biasl on the flanges of the packings-'serves to urge them firmly and evenly into'contactjwith the wall of thepaddle chamber without the provision of spring expanders, although expanders may beprovidedif desired.

A feature of the invention therefore consists inA apaddle for fluid pressure motors ofgwhich the .each side.

packing members are cut from sheet material possessing elastic properties similar to rubber and assembled in the paddle unit without being preformed to the cupped form which the packing members will flnally assume when the paddle unit is assembled in the motor. Preferably the packing members are cut from sheet polyvinyl chloride, synthetic rubber, or the like of a thickness, forfexample offs'f Accordingto another Afeature of the invention, the two packing members are joined together at the top end of the paddle, in order that the maximumarc of movement of the paddle may be obtained without risk of the cupped ilanges at the top. end of'thezpaddle being sucked out of the auxiliary arcuate chamber when the paddle is in eitheltoflits extreme limiting positions.

According to a further feature of the invention, thevpaddle packing members, or at least those portions of the surfaces thereof which wipe against; the Walls. of thepaddle chamber, are unpolished or roughened, in korder to provide small cavitiesfor retaining oil and vgrease and distributing'itnover the walls of the paddle chamber; .Thissurface 4roughening may be produced byf'moulding ,orF calendaring the rubber-like, ma-y terialonlinenorfsimilarmaterial having a rough surface.`

From. another aspect, the'invention consists in an improved and novel method of assembling the paddle in k.a fluidV motor: without preforming the packing members toacuppedshape, andinzforming, 'the .cuppedflangesgto the packingv members during` .the actualassembling of the paddle unit inthe paddle chamber;

A:.further feature, of' therinvention consists in constructing the spacermember .b etweengthe two paddle .packingsasa single unit, preferably as a.,diecastinginto.which the motor'shaftis fitted. Prefer-ably the die-castingzis formed, integrally withoutwardlyextending projections which are adapted to pass throughapertures inthe packing member-sand outer plates vand to be finally spun or rivetedover 'or' fitted with nuts-to securethe packing members and outer plates to the inner unit. With this construction there are no apertures-which extend from one side of the paddle assembly to the other through which rivets pass so that leakage fromV one side to the other-through such aperturesis completely avoided.

In order that the invention may be more clearly understood, reference Will nowbe made to the accompanying drawings, in which- Fig; l isa perspectiveviewpof the paddle'before being'ttedin ther motor housing;

Fig, 2 is a section through the motor housing with the paddle in position.

Fig, 3. is a scrap view showing the paddle being inserted intothe motor housing.

Fig. 4 is an-end view of Fig. 3.

Fig. 5, shows a section throughthe paddle during assembly of the components thereof.

Referring to the drawings, the paddle comprises a lcentral spacer 3 constructed asa diecasting,l such asa zinc-base die-casting, cast in,- tegrally with two projections 4 extending from One of these Aprojections 4' is made 'longer than the other three. The .two packing members I, IL' of sheet polyvinyl chloride or like material, are fitted' toopposite sides of the central membenbeing formed with apertures which 'fit-over the projections 4. Outer metal plates 42, '2' are then rassembled Vover theouter surfaces of .the packing members, these outer plates also be- -ing provided with apertures to t over the projecytions 4. A cross-section of the paddle as so far 'assembled is shown in Figure 5.

4constructed of polyvinyl chloride or like material 'and shaped as shown in Figure 4, is fitted over the projection 4' between two metal Washers I9 and`-20. The end of the projection is then riveted over to hold these washers and the valve member I1 in position on the paddle assembly. The central member 3 is cored with apertures into fwhch the motor shaft 5 and the valve shaft 5',

carrying the valve operating member 20, are respectively tted, for example by a force fit. These shafts may be formed at their ends which lit into cored apertures with longitudinal grooves or {splines-in order positively to interlock the shafts withthe casting.

The packing members are made larger than the cross-section of the paddle chamber 6 of the motor by an amount approximately equal to the width of the flanges to be-formed around each packing member, and the outer metal plates 2, 2

o'f'the paddle assembly are made of such a size that they will clear the innerv walls of the paddle chamber 6 by an amount less than the thickness of the sheet material from which the packing members I, I are made. The plates 2, 2' are preferably formed inwardly at l, the central member 3 being similarly shaped, so that the thickness of the paddle unit can be made as small as possible to permit the maximum arc of swing to be obtained. If desired, thev plates 2, 2' may also be provided with small notches I6 in their periph- "eries inA order to clear the curved corners of the "auxiliary arcuate chamber I and thus still fur- K ther increase the maximum are of swing.

Ar'Thetop and bottom ends of the outer plates 2 and 2 are also bent inwardly in order to cause the top and bottom ends of the packing members to be inclined slightly inwards as shown, for exs 'ample by 8 in Fig. 3. Preferably, however, the top ends of the two packing members are joined together. This may be most easily eiected by Acutting the two packing members as an integral unit from the sheet material, the two members being joined at 9.

To assemble the complete paddle unit in the motor, the unit is just entered into the paddle chamber E with the peripheral zones of the packing members bent inwardly towards one another. The disposition of the peripheral zones of the packing members in this way is facilitated by the curved forms of the half bearings I0 in the top edges of the casting forming the paddle chamber 6, in which the paddle shaft will nally rest. The paddle unit is then pushed vertically downwards into the`casting,`during which the movement of the side peripheral zones of the packing members are each progressively folded over inwards, as shown in Figs. 3 and 4. Until the paddle unit almost reaches the bottom of the paddle chamber, the bottom peripheral zones of the packing members remain unfolded, but when these bottom zones touch the bottom of the chamber 6, continued downward movement of the ypaddle unit causes these bottom zones to fold over inwardly and assume the positions shown in Fig. 2.. This folding over of the bottom zones is-assisted by the arcuate'form of the bottom of the paddle chamber Band also by the fact that the bottom Zonesfare biassed inwardly by the'ends of the outerplates 2, 2. Due'to the elastic properties of the packing members, the curved portio-ns of the flanges between the side and bottom zones are formed without the production of wrinkles whichwould cause leakage past the packing. F'

The insertion of the paddle unit into the paddle chamber as above described is facilitated by the application of grease to the paddle. This' may be conveniently applied to the space between the peripheral zones of the two packing members.

After the simple assembly operation above described has been completed and the paddle shaft is tted and resting in its half bearings Il! at the top edge of the paddle chamber, and the extension bearing il is resting in the correspondingv recess I2 in the casting in known manner, it is only necessary to t the top cover I3 of the motor which incorporates the-auxillary arcuate chamber III for accommodating the top end of the paddle. The tti'ng of the top cover automatically folds in the topr portionsof the sides of the packing members.A If thetwo packing members are separate (instead of. being joined together at their top ends as shown) these top edges will be folded inwards upon engaging the arcuate surface of the auxiliary chamber I (assisted by the fact that these edges are already inwardly inclined by the shape of the top ends of the outer plates 2, 2') with a smooth surface to the curved corner portions of the flanges. The cover is then' secured in position by means of screws I5.

As above described, the paddle also carries the valve I'I which 'serves to seal off the motor chamber, by engaging with the seating I8, when the paddle isfin the parked position.

The feature of joining the paddle packing members together at their top ends as above described can be used with advantage whetherv the packing members are made from synthetic rubber, leather or other material. In paddle type motors as hitherto constructed, leakage past the packing at the top end of the paddle is likely, particularly under' the conditions obtaining upon reversal of the paddle movement at each end of its stroke. It has been found that when the paddle is at `either of its extreme limiting positions, there is a tendency for the portion of the paddle packing working in the auxiliary chamber to be pulled out ofthe auxiliary chamber by the applied suction. When'the paddle reaches the end of its stroke in one direction, the flange of the top end pore tion of the packing member which in that position is adjacent the main chamber usually partially protrudes into the main chamber owing to the thickness of the paddle. Thus when the suction is applied to this side of the paddle to move it in the opposite direction, this protruding portion of the flange is subjected to the 'suction which tends to draw it out of the auxiliary chamber and cause leakage fof air past the flange, and also tends, upon movement in said opposite direction, to fold back' thev flange sogthat the top edge of the packing may become wrinkled or damaged as it is moved into the auxiliary chamber by the effect of the suction on the main body of the paddle inthe main chamber.' For this reason, the maximum arc of movement of the paddle has hitherto had to be limited so that this top flange will not fold back upon reversal.

ByV Joining the; two. top flanges together, the .possibility of the flanges reversing their directionsA is avoided. The paddlepackings may be formed in one piece as, above described or in two or more parts which are subsequently joined together;

The .method of constructing the central member 3 of the paddle assembly as a single diecasting also presents advantages even if the packing members are made, as hitherto, of leather. Previously the spacing member has generally beenv constructed of two metal plates, sometimes provided with flanges around their edges as` described for, example in British speciiications. Nos. 237,455 and 444,452; the -components' of the paddle assembly being secured together by rivets whichv passv through the outer plates,D the packing, member, the inner plates andA also. throughA anAV aperture. in the transverse shaft about which the paddle rocks. In, order that the motor vmay operate on the` lowest possible degree- `of suction, it is important that leakage from oneA sideof, the paddle to the. other should be reduced as. much. as possible and also that the paddle shouldv move with the minimum friction Within. the paddlechamber. The .method of constructing the paddle as hitherto employed possesses such difficulties in manufacture by mass production methods that these desiderata cannot. be uniformly obtained. 'I2'husA for. example,4 since the rivets securing the paddle assembly togetherpass through apertures. which extend from :one sideof thev paddle to,- theother, a leak often occurs through. this aperture which reduces. the eiiiciency of the motor. If the rivets aree very tightly sealed over to reduce this leakage, it often occurs that the two. inner metal members and the packing members locatedl thereby become. forced out of alignment as a result. of which the packing members may bear unevenly on the. Wallsr of the 4paddle chamber,-` thereby increasing the fric.- tion and also4 giving rise to the possibility of leakage around the packing Vmember. Furthermore, if` the assembly is, thus tightly riveted, unless' very; great care is taken to ensure that` the, transverse shaft about which the paddle rocksris exactly at right angles to the longitudinal axisl of thepaddle, then again the paddle,- packing will bear more heavily against one wall of the; paddle chamber than the other, again; l with increaseof friction and risk of leakage;

By Vreason of. constructing the; central member as a solid unitary member according to this invention,Y any .rivet passed therethrough for assemblingv the outer plates and the packing members, to the central unit may be tightly riveted without anyA possibility of causing' misalignmentA as withA the previous constructions. Preferably, however, rivets which pass from one side to the-other of' the paddle are completely eliminatedA and the rivets are formed by the integrally: castv projections, as above described, so: that leakage from one side of the paddle to the.y other; by reasonoffrrivet. apertures is completely avoided.

Furthermorey since the Adriving shaft is fitted into anv aperture or recess in the central unit, which aperture or recess can be accurately formed in ythe unit, lfor example during the die-casting operation,.the;sha`ft is accurately positionedwith respect to. the. paddle. even when made in commarcial.v mass production.

By die-casting the central unitgLit 'can `be-easily -cute an increased arc of. movement. The arco! movement of a motor'of the type` tov which. this invention relates is` generally restricted. by the paddle engaging with. the edges of the auxiliary arcuate chamber, and by means of this novel construction the inner unit-can be shaped: and Waisted to increase its arc of. movement, the short end of the inner unit being curved inwardlyI to avoidv the packing members from moving out'iof theA auxiliary arcuate chamberl when the paddle reachesV the extreme limit of its increased arc` of movement. By means of this construction an arc of movement4 of about 140 can be obtained' com.- pared with the usual arc of 126.

The shaft 5' carrying the valve operating member2|ll may be accurately located in the die-cast central unitv 3. If desired, the shaft 5' and the valve operating member 21'! carried thereby may be die-cast integrally with the inner unit.. The valve operating member 20 has faces for actuating the valveby an over-centre action when it reaches the limit of its stroke (the construction ofthe valve mechanism is well-known in the art) and since the invention enables the valve operating member tov be accurately located with re.- spect to the paddle, accurate timing between the valve andthe movement of. the paddle may be obtained by commercial manufacturing methods, this timing being particularly important where the paddle executes an' increased arc offmovement as-above described.

Whilst a particular embodiment of the-invention has been described, it will be understood that various modifications may be made without departing from the scope of the invention. Thus if it be desired to reduce the weight of theinner unit, it may be cored out to form cavities such as indicated at 3', which cavities may, if desired, be used as a reservoir or reservoirs for grease or other lubricant, grooves or apertures beingprovided in the casting connecting the reservoir cavity or cavities with the peripheral edges-ofthe casting.

Moreover, the motor shaft needl not be inserted into an aperture in the central member as described but can be connected to the paddle in a. floating manner, for example by constructing the motor shaft as a bent shaft which fits into an appropriately shaped aperture or cavity formed in thedie-casting. For example, an L-shapedfcavity may be formed in the die casting to receive the bent motor shaft. which is held in position by securing the packing members and outer plates in position.

I claimz.

1. A iiuid pressurev motor of .the oscillating paddle type comprising a paddle chamber and4 a paddle movable in said chamber, said paddle comprising a spacer having a pair of cupped packing members made of. rubber-like material positioned on opposite sides of said spacer with their cuped edges facing towards one-another, anda pair of substantially rigid outer members secured respectively over the outer surfaces of the packingy members, said outer members being of such a size that the clearance between the periphery of an outer member and: the wall of the paddle chamber is insufficient to permit thefiange to be sucked orotherwise moved so 4that it, or a part thereof, can lface in the opposite direction lto that Ain which it is designed to operate.

2. Aiiuid pressure motor of theroscillating'padidle type comprising a paddle chamber andY a .paddlev movablen'said chamber, said paddle-com- 9.4 prising a spacer having a pair. of cupped packing members madeof rubber-like material positioned von opposite sides ofsaid spacer with their cupped edges facing towards one another, and a pair of substantially rigid outer members securedrespectively over the outer surfaces of the packing members, said outer members being of sucha size that the clearance between the periphery of an outer member and the wall of--the paddle chamber is not greater than the thickness of the material of the flange of the adjacent packing member at al1 points around said periphery, except for any small portionsv of said periphery which may be cut away and are sufficiently small to prevent the adjacent part of the flange from being turned inside out under the operating conditions of the motor, and except at any parts of said periphery where the flanges of the two packing members are joined toegther. Y

.3. Device as claimed in claim l2, in which the packing members are cut from sheet material of a size larger than the cross-section of the paddle chamber, the edges of the packing members being folded over to form the flanges by the operation of inserting the paddle into the paddle chamber.

vfi. A paddle for fluid pressure motorspff'the oscillating paddle type, comprising a spacer, Aa pair of packing members cut from sheet rubberlike material and assembled one on either side of the spacer, a rigid platemember positioned over the outer surface of each packing'm'ember, and means for securing the :outer members to the spacer with the packing members secured therebetween. 1

5. Device as claimed in claim 4, wherein the two packing members are formed integrally from sheet material, being joined together at the region which forms the top end of the paddle. 1

6. Device as claimed in claim 5, wherein at least the bottom ends of each plate member are bent inwardly to incline the bottom ends of the packing members inwardly.

7. A paddle as claimed in claim 6, wherein the top ends of the metal plates are also bent inwardly.

8. Method of assembling a paddle in a fluid motor of the oscillating paddle type, which consists in constructing the paddle with packing members cut from sheet rubber-like material and of larger size than the cross-section of the paddle chamber, and folding the edges of the packing member inwardly by the operation of inserting the paddle into the paddle chamber.

9. Method of assembling the paddle unit of a fluid pressure motor in the paddle chamber, which consists in positioning the paddle, having unflanged packing members of rubber-like material, above the half bearings of the paddle chamber and entering the paddle into the chamber with the peripheral side zones of the packing members bent inwardly towards one another, and advancing the paddle into the chamber to complete the folding over of the side zones and the bottom peripheral zones of the packing members.

10. A paddle for a fluid pressure motor of the oscillating paddle type, comprising a central diecasting, at least one projection extending from opposite faces of said diecasting and formed integrally therewith, a packing member positioned over each face of the diecasting with the projections passing through apertures therein, a rigid plate member positioned over y the outer surfaces of said packing members with the projections passing through apertures therein, and

means on the free ends lof said projections for securing the packing members and plate mem-- bers to the central diecasting.

11. A paddle as claimedin claim 10, wherein at least the bottom ends of the plate members are inclined inwardly towards` the central diecasting.

12. Aipaddle for arfluid pressure' motor of the oscillating paddle type,v comprisingA a central member, at least one projection extending from opposite faces ofv said central member, a packing member positioned over each face of the central member with the projections passing through apertures therein, a rigid member, positioned over the outer surfaces of said packing members withthe Vprojections passing through apertures thereimand means on the free ends of said projections for securing the packing members and rigid members to the central member.

13. A paddle as claimed in claim 12, wherein the two packing members havetheir topl edges joined together.

' 141A paddle as claimed in claim 13, wherein the two packing members are formed integrally and applied to the central member by folding about the top end of the central member.

15. A fluid pressure motor of the oscillating paddle type, comprisinga paddle chamber, a paddie,` movable inrsaid chamber and comprising a central diecasting, at least oneprojection extendingfrom opposite faces of said diecasting and formed integrally therewith, a-.packing member made of rubber-like materiall positioned over each ofthe Vdiecasting with the projections passing through apertures'therein, a rigid plate member positioned over the outer surfaces of said packing members with the projections passing through apertures therein, and means on the free ends of said projections for securing the packing members and plate members to the central diecasting, said plates being of such a size that the clearance between the periphery of an outer plate and the Wall of the paddle chamber is insufficient to permit the flange to be sucked or otherwise moved so Vthat it or a part thereof can face in the opposite direction to that in which it is designed to operate.

16. A fluid pressure motor as claimed in claim 15, in which the packing members on opposite sides of the paddle are joined together at least at the top of the paddle.

17. For a fluid pressure motor of the oscillating paddle type a paddle comprising a spacer having a rocker shaft extending from the side thereof at a point between the top and bottom ends of the spacer but closer to its top end than to its bottom end, two cupped packing members disposed respectively on opposite surfaces of said spacer with their cupped edges extending around the entire periphery of the spacer and facing towards one another, and means joining said packing members together at the top of the paddle, said packing members otherwise having their edges separate around substantially their entire peripheries.

18. For a fluid pressure motor of the oscillating paddle type, a paddle comprising a spacer having .a rocker shaft extending from the side thereof at a point between the top and bottom ends of the spacer but closer to its top end than to its bottom end, packing members positioned on opposite surfaces of said spacer, said packings being made from a single piece of rubber-like material which is of a width greater than the width of the spacer and of a length greater than twice the length of afname 1l the Aspacer and which is folded around the top of the spacer and louter plates .positioned against the outer surfaces .of "the packing members land secured to the spacer.

19. A fluid pressure motor of the oscillating `paddle type comprising a motor housing .having a main arcuate paddle chamber, a paddle'having a rocker shaft extending from the side thereof at a point between the top `and bottom ends ofthe paddle but closer to its top end than to its bottom end, said paddle being positioned -within the housing with said rocker shaft movable in a bearing carried by the housing coaxial with the -oentre of curvature of the main .arcuate chamber. said housing also being formed with an auxiliary arcuate chamber concentric with the main arcuate chamber within which the top endiof the paddle moves whilst the bottom end 4of the paddle moves in the main arcuate chamber, said ,paddle comprising a spacer from which the 4rocker shaft projects, and cupped packing members rpositioned on opposite sides of said spacer with theircupped edges facing towards one another, said packings being out from a single sheet of rubber-like material which is folded around the -top `end Iof the spacer and secured in position on opposite .sides of the spacer.

20. A iluid pressure motor as 'claimedin claim 19, wherein the paddle packings are cut from sheet rubber-like material.

21. A fluid pressure motor of the oscillating paddle type comprising a motor housing having a main arcuate paddle chamberi a paddle having a rocker shaft extending from the side thereof at a point between the top' and bottom ends of the 1'2 paddle but closer to its ytop :end than ,to its rbottom endfsaid paddle being positioned within the housing with said rocker shaft movablein a bearing carried bythe housing coaxial with the centre of -curvature of the main arcuate chamber, said housing also being formed with an auxiliary arcuate chamber concentric with the main arcuate chamber within which the top end of thepaddle moves Whilst the bottom end vof the paddle moves in the main Yarcuate chamber, said paddle comprising a spacer from which the rocker yshaft projects, cupped vpacking members positioned on opposite sides of .said spacer with their cupped edges .facing towards one another, and means forjoining anges of said :packings together at the top ofthe paddle.

'WILLIAM EDWARD O'SHEI.

REFERENCES CITED The following references are of record in the ille -lo'f this patent:

UNITED STATES PATENTS Number .Name Date 1,019,388 Weber et al Mar. 5, .1912 1,565,493 Oishei et al Dec. 15, 1925 1,777,143 Hueber Sept. 30, 1930 .2,012,817 Horton et al Aug. 27 1935 y2,302,109 Dodge Nov. 17, 1942 y2,314,493 Guy Mar. 23, 1943 2,553,973 Keller et al May 21. 1951 FOREIGN PATENTS Number Country .Date

391,107 GreatBritain Apr. 18, 1933 

